The long-term goal is to develop a rehabilitation strategy to prevent the deleterious neural, muscular, and skeletal secondary complications that follow complete spinal cord injury (SCI). As many as twenty thousand Americans sustain an SCI each year, making it a public health concern of primary importance. Secondary complications (muscle atrophy, osteoporosis, bone fractures, spasticity) in the decades after SCI cost society between 4 and 7 billion dollars annually. A method to prevent these complications would not only provide substantial savings, but could also profoundly improve the quality of life of people with SCI and keep them as viable candidates for the future cure. Recently, we verified that a certain dose of stress preserved bone and muscle physiology in the lower leg for 2 years following SCI. These findings suggest that a novel approach to apply various doses of muscle stress to the entire lower extremities early after paralysis may be an important mechanism to shape spinal circuitry, muscle, and bone reorganization following disuse from SCI. Three specific aims will test these hypotheses using an innovative method to induce various doses of stress to the lower extremities during stance using neuromuscular electrical stimulation. Aim 1 will compare 3 doses of muscle stress (0, 40, 80% BW) on muscle physiological properties (fatigue, force, potentiation) over the first year following SCI. Aim 2 will compare 4 doses of stress (0, 40, 80, and 120% BW) on skeletal bone mineral density over the first year following SCI. Aim 3 will compare various doses of muscle stress on spastic hypertonia and H-reflex suppression over the first year following SCI. A novel component of this study is its emphasis on feasibility and dose specificity. This research is grounded in scientific principles, but also has the potential to rapidly translate to the clinical milieu to influence health quality. In the next several decades, a cure for spinal cord injury is a realistic possibility. Without a method to preserve the integrity of paralyzed lower limbs, people injured today with SCI will be left as "inappropriate candidates" for reintroduction to standing and walking, should a cure be found. In the interim, preservation of neural, muscular, and skeletal properties after SCI may contribute to a healthier individual. The proposed method not only has excellent potential for efficacy, but is also likely to be economical and easily integrated into the daily lives of people with SCI. [unreadable] [unreadable] [unreadable] [unreadable] [unreadable] [unreadable] [unreadable]